Radio frequency power amplifier control device

ABSTRACT

The present disclosure relates to a radio frequency power amplifier (RFPA) control device. The RFPA control device may include an input signal processing module configured to process an input signal into two signals. A first signal may be used for signal detection, and a second signal may be used for signal amplification. The RFPA control device may also include a delay module. The delay module may be disposed between the input signal processing module and an adjustment module. The delay module may be configured to determine a delay of the second signal such that the second signal and the control signal roughly simultaneously reach the adjustment module.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This application claims priority of Chinese Application No.201910768760.X, filed on Aug. 20, 2019, and Chinese Application No.201921357717.6, filed on Aug. 20, 2019, the contents of each of whichare hereby incorporated by reference.

TECHNICAL FIELD

The present disclosure generally relates to the field of radio frequencypower amplification, and more specifically relates to a radio frequencypower amplifier (RFPA) and a RFPA control device.

BACKGROUND

Magnetic resonance imaging (MRI), a non-invasive imaging technique thatcan obtain image data of internal structures of an object withoutperforming an invasive procedure on the object, which has a broad rangeof uses in the medical field. A radio frequency power amplifier (RFPA)is an important component of an MRI system. The RFPA receives a seriesof pulses generated by an external RF source as its input signals, andgenerates a series of amplified pulses as its output signals. The outputsignals are used to drive RF coils. Thus, the performance of the RFPAmay affect the quality of image(s) generated by the MRI system.

The RFPA is composed of multiple nonlinear elements, and accordingly theRFPA generally exhibits nonlinear characteristics. Specifically, theRFPA shows various amplitude amplification capabilities (oramplification factor) and outputs different phases on the basis of thedifferent sizes of radio frequency signal power (e.g., different seriesof pulses), thus, resulting in non-linearity. Medical staff often wantsthe RFPA to be linear. That is, for different sizes of radio frequencysignal power, the radio frequency power amplification capability isconsistent, with the same amplitude magnification and the same outputphase. Therefore, an additional design adjustment device is required toadjust the amplitude magnification and output phase of the RFPA toachieve constant gain and constant phase, which is called nonlinearcorrection.

The calibration process of the traditional nonlinear correction devicemainly includes three steps: first, detecting the input radio frequencysignal; second, calculating the adjustment amount of the input radiofrequency signal that needs to be adjusted; and third, compensating thegain and output phase of the radio frequency power amplifier itselfthrough the regulator.

However, the conventional nonlinear correction device has a big problem:the correction itself comprises data processing and transmission ofcontrol signals, resulting in that the time at which the control signalreaches the adjustment device lags behind the input timing of the radiofrequency signal (i.e., the time at which the radio frequency signalreaches the adjustment device). Especially, when the input radiofrequency signal is a rapidly changing modulated signal, the timeinterval caused by the hysteresis leads to poor nonlinear correctionresults of the RFPA, which leads to poor imaging stability and evenartifacts of the MRI system. Therefore, it is necessary to design acontrol device (also referred to as an RFPA control device) coordinatewith the RFPA to achieve constant gain and constant phase, which is alsoknown as nonlinear correction.

SUMMARY

In one aspect of the present disclosure, a radio frequency poweramplifier control device is provided. The radio frequency poweramplifier control device may be coupled to a radio frequency poweramplification module. The radio frequency power amplifier control devicemay include an input signal processing module and a delay module. Theinput signal processing module may be configured to process an inputsignal into at least two signals. A first signal of the at least twosignals may be used for signal detection. A second signal of the atleast two signals may be used for signal amplification. The delay modulemay be disposed between the input signal processing module and anadjustment module. The delay module may be configured to determine adelay of the second signal such that the second signal and the controlsignal roughly simultaneously reach the adjustment module.

In some embodiments, the radio frequency power amplifier control devicemay also include the adjustment module and a signal processing andcontrol module. The adjustment module may be connected to the inputsignal processing module and the radio frequency power amplificationmodule, respectively. The adjustment module may be configured to adjustat least one feature of the second signal. The signal processing andcontrol module may be connected to the input signal processing moduleand the adjustment module, respectively. The signal processing andcontrol module may be configured to generate a control signal based onat least one feature of the first signal. The control signal may beconfigured to control a degree of the adjustment of the at least onefeature of the second signal.

In some embodiments, the signal processing and control module mayinclude an input signal detection sub-module, and a signal processingand control sub-module. The input signal detection sub-module may beconnected to the input signal processing module and configured to detectthe at least one feature of the first signal. The signal processing andcontrol sub-module may be connected to the input signal detectionsub-module and the adjustment module, respectively. The signalprocessing and control sub-module may be configured to generate thecontrol signal based on the at least one feature of the detected firstsignal.

In some embodiments, the input signal detection sub-module may includeat least one of a detector, a diode, or a phase discriminator.

In some embodiments, the signal processing and control sub-module mayinclude an adjustable delay unit configured to impose an adjustabledelay on the control signal.

In some embodiments, a total transmission time from a moment that thefirst signal is transmitted to the signal processing and control moduleto a moment that the control signal is transmitted to the adjustmentmodule may be composed of a first transmission time, a secondtransmission time, a third transmission time, and a fourth transmissiontime. The first transmission time may be a time that the input signaldetection sub-module detects the at least one feature of the firstsignal. The second transmission time may be a time that the signalprocessing and control sub-module processes the first signal andgenerates the control signal. The third transmission time may be a timeof transmitting the control signal to the adjustment module. The fourthtransmission time may be an adjustable delay time imposed by theadjustable delay unit of the signal processing and control sub-module.

In some embodiments, the adjustable delay unit may adjust the fourthtransmission time to change a time difference between the totaltransmission time and the delay of the second signal such that thesecond signal and the control signal roughly simultaneously reach theadjustment module.

In some embodiments, the adjustment module may include at least one of acontrollable attenuator, or a phase shifter.

In some embodiments, the at least one feature of the first signal mayinclude amplitude and/or phase. The at least one feature of the secondsignal may include amplitude and/or phase.

In some embodiments, the radio frequency power amplification module maybe configured to receive and amplify the adjusted second signal togenerate an output signal.

In some embodiments, the radio frequency power amplifier control devicemay include an output signal processing module. The output signalprocessing module may be connected to the radio frequency poweramplification module. The output signal processing module may beconfigured to process the output signal into at least two outputsignals. A first output signal of the at least two output signals may beused for signal detection, and a second output signal of the at leasttwo output signals may be transmitted to a load.

In some embodiments, the signal processing and control module mayfurther include an output signal detection sub-module. The output signaldetection sub-module may be connected to the output signal processingmodule and the signal processing and control sub-module, respectively.The output signal detection sub-module may be configured to detect atleast one feature of the first output signal. The signal processing andcontrol sub-module may be configured to generate the control signalbased on the at least one feature of the first signal and the at leastone feature of the first output signal.

In some embodiments, the delay module may include at least one of a LCfilter, a surface acoustic wave filter, or a delay line.

In another aspect of the present disclosure, a method for controlling aradio frequency power amplifier is provided. The method may beimplemented on a computing device including at least one processor, atleast one storage device, and a communication platform connected to anetwork. The method may include processing, by an input signalprocessing module, an input signal into at least two signals, wherein afirst signal of the at least two signals is used for signal detection,and a second signal of the at least two signals is used for signalamplification; generating, by a signal processing and control module, acontrol signal based on at least one feature of the first signal;determining, by a delay module, a delay of the second signal such thatthe second signal and the control signal roughly simultaneously reach anadjustment module; and adjusting, by the adjustment module, at least onefeature of the second signal based on the control signal.

In some embodiments, the generating a control signal based on at leastone feature of the first signal may include detecting the at least onefeature of the first signal, and generating the control signal based onthe at least one feature of the detected first signal.

In some embodiments, the method may also include amplifying the adjustedsecond signal to generate an output signal by a radio frequency poweramplification module.

In some embodiments, the method may include processing the output signalinto at least two output signals by an output signal processing module.A first output signal of the at least two output signals may be used forsignal detection, and a second output signal of the at least two outputsignals may be transmitted to a load.

In some embodiments, the generating a control signal based on at leastone feature of the first signal may include detecting at least onefeature of the first output signal, and generating the control signalbased on the at least one feature of the first signal and the at leastone feature of the first output signal.

In some embodiments, the delay module may include at least one of a LCfilter, a surface acoustic wave filter, or a delay line.

In yet another aspect of the present disclosure, a radio frequency poweramplifier is provided. The radio frequency power amplifier may include aradio frequency power amplifier control device and a radio frequencypower amplification module. The radio frequency power amplifier controldevice may include an input signal processing module, an adjustmentmodule, a signal processing and control module, and a delay module. Theinput signal processing module may be configured to process an inputsignal into at least two signals. A first signal of the at least twosignals may be used for signal detection, and a second signal of the atleast two signals may be used for signal amplification. The adjustmentmodule may be connected to the input signal processing module andconfigured to adjust at least one feature of the second signal. Thesignal processing and control module may be connected to the inputsignal processing module and the adjustment module, respectively. Thesignal processing and control module may be configured to generate acontrol signal based on at least one feature of the first signal. Thecontrol signal may be configured to control a degree of the adjustmentof the at least one feature of the second signal. The delay module maybe disposed between the input signal processing module and theadjustment module. The delay module may be configured to determine adelay of the second signal such that the second signal and the controlsignal roughly simultaneously reach the adjustment module. The radiofrequency power amplification module may be configured to receive andamplify the adjusted second signal to generate an output signal.

Additional features will be set forth in part in the description whichfollows, and in part will become apparent to those skilled in the artupon examination of the following and the accompanying drawings or maybe learned by production or operation of the examples. The features ofthe present disclosure may be realized and attained by practice or useof various aspects of the methodologies, instrumentalities andcombinations set forth in the detailed examples discussed below.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is further described in terms of exemplaryembodiments. These exemplary embodiments are described in detail withreference to the drawings. The drawings are not to scale. Theseembodiments are non-limiting exemplary embodiments, in which likereference numerals represent similar structures throughout the severalviews of the drawings, and wherein:

FIG. 1 is a schematic diagram illustrating an exemplary MRI systemaccording to some embodiments of the present disclosure;

FIG. 2 is a schematic diagram illustrating exemplary hardware and/orsoftware components of a computing device on which the processing devicemay be implemented according to some embodiments of the presentdisclosure;

FIG. 3 is a schematic diagram illustrating exemplary hardware and/orsoftware components of a mobile device according to some embodiments ofthe present disclosure;

FIG. 4A is a schematic diagram illustrating an exemplary radio frequencypower amplifier (RFPA) control device according to some embodiments ofthe present disclosure;

FIG. 4B is a schematic diagram illustrating an exemplary radio frequencypower amplifier (RFPA) according to some embodiments of the presentdisclosure;

FIG. 5A is a schematic diagram illustrating an exemplary radio frequencypower amplifier (RFPA) control device according to some embodiments ofthe present disclosure;

FIG. 5B is a schematic diagram illustrating an exemplary radio frequencypower amplifier (RFPA) according to some embodiments of the presentdisclosure;

FIG. 6A is a schematic diagram illustrating an exemplary radio frequencypower amplifier (RFPA) control device according to some embodiments ofthe present disclosure;

FIGS. 6B and 6C are schematic diagrams illustrating an exemplary radiofrequency power amplifier (RFPA) according to some embodiments of thepresent disclosure; and

FIG. 7 is a flowchart illustrating an exemplary process for adjusting asecond signal according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth by way of examples in order to provide a thorough understanding ofthe relevant disclosure. However, it should be apparent to those skilledin the art that the present disclosure may be practiced without suchdetails. In other instances, well known methods, procedures, systems,components, and/or circuitry have been described at a relativelyhigh-level, without detail, in order to avoid unnecessarily obscuringaspects of the present disclosure. Various modifications to thedisclosed embodiments will be readily apparent to those skilled in theart, and the general principles defined herein may be applied to otherembodiments and applications without departing from the spirit and scopeof the present disclosure. Thus, the present disclosure is not limitedto the embodiments shown, but to be accorded the widest scope consistentwith the claims.

The terminology used herein is for the purpose of describing particularexample embodiments only and is not intended to be limiting. As usedherein, the singular forms “a,” “an,” and “the” may be intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprise,”“comprises,” and/or “comprising,” “include,” “includes,” and/or“including,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

It will be understood that the term “system,” “unit,” “module,” and/or“block” used herein are one method to distinguish different components,elements, parts, section or assembly of different level in ascendingorder. However, the terms may be displaced by other expression if theyachieve the same purpose.

Generally, the word “module,” “unit,” or “block,” as used herein, refersto logic embodied in hardware or firmware, or to a collection ofsoftware instructions. A module, a unit, or a block described herein maybe implemented as software and/or hardware and may be stored in any typeof non-transitory computer-readable medium or another storage device. Insome embodiments, a software module/unit/block may be compiled andlinked into an executable program. It will be appreciated that softwaremodules can be callable from other modules/units/blocks or fromthemselves, and/or may be invoked in response to detected events orinterrupts. Software modules/units/blocks configured for execution oncomputing devices (e.g., processor 210 as illustrated in FIG. 2) may beprovided on a computer readable medium, such as a compact disc, adigital video disc, a flash drive, a magnetic disc, or any othertangible medium, or as a digital download (and can be originally storedin a compressed or installable format that needs installation,decompression, or decryption prior to execution). Such software code maybe stored, partially or fully, on a storage device of the executingcomputing device, for execution by the computing device. Softwareinstructions may be embedded in firmware, such as an EPROM. It will befurther appreciated that hardware modules/units/blocks may be includedof connected logic components, such as gates and flip-flops, and/or canbe included of programmable units, such as programmable gate arrays orprocessors. The modules/units/blocks or computing device functionalitydescribed herein may be implemented as software modules/units/blocks,but may be represented in hardware or firmware. In general, themodules/units/blocks described herein refer to logicalmodules/units/blocks that may be combined with othermodules/units/blocks or divided into sub-modules/sub-units/sub-blocksdespite their physical organization or storage.

It will be understood that when a unit, engine, module or block isreferred to as being “on,” “connected to,” or “coupled to,” anotherunit, engine, module, or block, it may be directly on, connected orcoupled to, or communicate with the other unit, engine, module, orblock, or an intervening unit, engine, module, or block may be present,unless the context clearly indicates otherwise. As used herein, the term“and/or” includes any and all combinations of one or more of theassociated listed items.

These and other features, and characteristics of the present disclosure,as well as the methods of operation and functions of the relatedelements of structure and the combination of parts and economies ofmanufacture, may become more apparent upon consideration of thefollowing description with reference to the accompanying drawings, allof which form a part of this disclosure. It is to be expresslyunderstood, however, that the drawings are for the purpose ofillustration and description only and are not intended to limit thescope of the present disclosure. It is understood that the drawings arenot to scale.

An aspect of the present disclosure relates to a radio frequency poweramplifier (RFPA) control device configured to adjust an input signal toimplement a nonlinear correction of a radio frequency power amplifier(RFPA). The RFPA control device may be coupled to a radio frequencypower amplification module. The RFPA control device may include an inputsignal processing module, an adjustment module, a signal processing andcontrol module, and a delay module. The adjustment module may beconnected to the input signal processing module and the radio frequencypower amplification module, respectively. The signal processing andcontrol module may be connected to the input signal processing moduleand the adjustment module, respectively. The delay module may bedisposed between the input signal processing module and the adjustmentmodule.

The input signal processing module may be configured to process an inputsignal into two signals. A first signal may be used for signaldetection, and a second signal may be used for signal amplification. Theadjustment module may be configured to adjust at least one feature ofthe second signal. The signal processing and control module may beconfigured to generate a control signal based on at least one feature ofthe first signal. The control signal may be configured to control adegree of the adjustment of the at least one feature of the secondsignal. The delay module may be configured to determine a delay of thesecond signal such that the second signal and the control signal roughlysimultaneously reach the adjustment module.

In some embodiments, the RFPA can be used in various applications.Examples of such applications may include broadcasting, satellitecommunications, cellular communications. In some embodiments, the RFPAmay be used in a magnetic resonance imaging (MRI) system. For example,the RFPA may amplify an input signal and generate an amplified outputsignal. The amplified output signal may be transmited to RF coils. Moredescriptions may be found in, e.g., FIG. 1 and the descriptions thereof.

FIG. 1 is a schematic diagram illustrating an exemplary MRI systemaccording to some embodiments of the present disclosure. As illustrated,the MRI system 100 may include an MRI scanner 110, a network 120, one ormore terminals 130, a processing device 140, and a storage device 150.The components in the MRI system 100 may be connected in various ways.Merely by way of example, as illustrated in FIG. 1, the MRI scanner 110may be connected to the processing device 140 through the network 120.As another example, the MRI scanner 110 may be connected to theprocessing device 140 directly as indicated by the bi-directional arrowin dotted lines linking the MRI scanner and the processing device 140.As a further example, the storage device 150 may be connected to theprocessing device 140 directly or through the network 120. As still afurther example, one or more terminals 130 may be connected to theprocessing device 140 directly (as indicated by the bi-directional arrowin dotted lines linking the terminal 130 and the processing device 140)or through the network 120.

The MRI scanner 110 may scan a subject located within its detectionregion and generate a plurality of data relating to the subject. In thepresent disclosure, “subject” and “object” are used interchangeably. TheMRI scanner 110 may include a magnet assembly, a gradient coil assembly,and a radiofrequency (RF) coil assembly (not shown in FIG. 1). In someembodiments, the MRI scanner 110 may be a close-bore scanner or anopen-bore scanner.

The magnet assembly may generate a first magnetic field (also referredto as a main magnetic field) for polarizing the subject to be scanned.The magnet assembly may include a permanent magnet, a superconductingelectromagnet, a resistive electromagnet, etc. In some embodiments, themagnet assembly may further include shim coils for controlling thehomogeneity of the main magnetic field.

The gradient coil assembly may generate a second magnetic field (alsoreferred to as a gradient magnetic field). The gradient coil assemblymay include X-gradient coils, Y-gradient coils, and Z-gradient coils.The gradient coil assembly may generate one or more magnetic fieldgradient pulses to the main magnetic field in the X direction (Gx), Ydirection (Gy), and Z direction (Gz) to encode the spatial informationof the subject. In some embodiments, the X direction may be designatedas a frequency encoding direction, while the Y direction may bedesignated as a phase encoding direction. In some embodiments, Gx may beused for frequency encoding or signal readout, generally referred to asfrequency encoding gradient or readout gradient. In some embodiments, Gymay be used for phase encoding, generally referred to as phase encodinggradient. In some embodiments, Gz may be used for slice selection forobtaining 2D k-space data. In some embodiments, Gz may be used for phaseencoding for obtaining 3D k-space data.

The RF coil assembly may include a plurality of RF coils. The RF coilsmay include one or more RF transmit coils and/or one or more RF receivercoils. The RF transmit coil(s) may transmit RF pulses to the subject.Under the coordinated action of the main magnetic field, the gradientmagnetic field, and the RF pulses, MR signals relating to the subjectmay be generated. The RF receiver coils may receive MR signals from thesubject. In some embodiments, one or more RF coils may both transmit RFpulses and receive MR signals at different times. In some embodiments,the function, size, type, geometry, position, amount, and/or magnitudeof the RF coil(s) may be determined or changed according to one or morespecific conditions. For example, according to the difference infunction and size, the RF coil(s) may be classified as volume coils andlocal coils.

In some embodiments, the MRI scanner 110 may also include a radiofrequency power amplifier (RFPA). The RFPA may receive a series ofpulses generated by an external RF source as the input signals, andgenerate a series of amplified pulses as the output signals. The outputsignals are used to drive RF coils. In some embodiments, the performanceof the RFPA may affect the quality of image(s) generated by the MRIsystem. To ensure the RFPA having a linear amplification ability, a RFPAcontrol device is used to adjust the input signal before amplified bythe RFPA. Details regarding the RFPA control device may be foundelsewhere in the present disclosure (e.g., FIGS. 4A-6C and thedescriptions thereof).

The network 120 may facilitate exchange of information and/or data. Insome embodiments, one or more components of the MRI system 100 (e.g.,the MRI scanner 110, the terminal 130, the processing device 140, or thestorage device 150) may send information and/or data to anothercomponent(s) in the MRI system 100 via the network 120. For example, theprocessing device 140 may cause, via the network 120, an input signalprocessing module to process an input signal into at least two signals.In some embodiments, the network 120 may be any type of wired orwireless network, or a combination thereof. The network 120 may beand/or include a public network (e.g., the Internet), a private network(e.g., a local area network (LAN), a wide area network (WAN)), etc.), awired network (e.g., an Ethernet network), a wireless network (e.g., an802.11 network, a Wi-Fi network), a cellular network (e.g., a Long TermEvolution (LTE) network), a frame relay network, a virtual privatenetwork (“VPN”), a satellite network, a telephone network, routers,hubs, switches, server computers, and/or any combination thereof. Merelyby way of example, the network 120 may include a cable network, awireline network, an optical fiber network, a telecommunicationsnetwork, an intranet, an Internet, a local area network (LAN), a widearea network (WAN), a wireless local area network (WLAN), a metropolitanarea network (MAN), a wide area network (WAN), a public telephoneswitched network (PSTN), a Bluetooth™ network, a ZigBee™ network, a nearfield communication (NFC) network, or the like, or any combinationthereof. In some embodiments, the network 120 may include one or morenetwork access points. For example, the network 120 may include wired orwireless network access points such as base stations and/or internetexchange points through which one or more components of the MRI system100 may be connected to the network 120 to exchange data and/orinformation.

The terminal 130 include a mobile device 130-1, a tablet computer 130-2,a laptop computer 130-3, or the like, or any combination thereof. Insome embodiments, the mobile device 130-1 may include a smart homedevice, a wearable device, a smart mobile device, a virtual realitydevice, an augmented reality device, or the like, or any combinationthereof. In some embodiments, the smart home device may include a smartlighting device, a control device of an intelligent electricalapparatus, a smart monitoring device, a smart television, a smart videocamera, an interphone, or the like, or any combination thereof. In someembodiments, the wearable device may include a bracelet, footgear,eyeglasses, a helmet, a watch, clothing, a backpack, an accessory, orthe like, or any combination thereof. In some embodiments, the smartmobile device may include a smartphone, a personal digital assistant(PDA), a gaming device, a navigation device, a point of sale (POS)device, or the like, or any combination thereof. In some embodiments,the virtual reality device and/or the augmented reality device mayinclude a virtual reality helmet, a virtual reality glass, a virtualreality patch, an augmented reality helmet, an augmented reality glass,an augmented reality patch, or the like, or any combination thereof. Forexample, the virtual reality device and/or the augmented reality devicemay include a Google Glass, an Oculus Rift, a HoloLens, a Gear VR, etc.In some embodiments, the terminal 130 may remotely operate the MRIscanner 110. In some embodiments, the terminal 130 may operate the MRIscanner 110 via a wireless connection. In some embodiments, the terminal130 may receive information and/or instructions inputted by a user, andsend the received information and/or instructions to the MRI scanner 110or to the processing device 140 via the network 120. In someembodiments, the terminal 130 may receive data and/or information fromthe processing device 140. In some embodiments, the terminal 130 may bepart of the processing device 140. In some embodiments, the terminal 130may be omitted.

In some embodiments, the processing device 140 may process data obtainedfrom the MRI scanner 110, the terminal 130, or the storage device 150.For example, the processing device 140 may cause an adjustment module toadjust at least one feature of a signal (e.g., a second signal) based ona control signal. The processing device 140 may be a central processingunit (CPU), a digital signal processor (DSP), a system on a chip (SoC),a microcontroller unit (MCU), or the like, or any combination thereof.In some embodiments, the processing device 140 may be a single server ora server group. The server group may be centralized or distributed. Insome embodiments, the processing device 140 may be local or remote. Forexample, the processing device 140 may access information and/or datastored in the MRI scanner 110, the terminal 130, and/or the storagedevice 150 via the network 120. As another example, the processingdevice 140 may be directly connected to the MRI scanner 110, theterminal 130, and/or the storage device 150, to access storedinformation and/or data. In some embodiments, the processing device 140may be implemented on a cloud platform. Merely by way of example, thecloud platform may include a private cloud, a public cloud, a hybridcloud, a community cloud, a distributed cloud, an inter-cloud, amulti-cloud, or the like, or any combination thereof. In someembodiments, the processing device 140 may be implemented on a computingdevice 200 having one or more components illustrated in FIG. 2 in thepresent disclosure.

The storage device 150 may store data and/or instructions. In someembodiments, the storage device 150 may store data obtained from theterminal 130 and/or the processing device 140. In some embodiments, thestorage device 150 may store data and/or instructions that theprocessing device 140 may execute or use to perform exemplary methodsdescribed in the present disclosure. In some embodiments, the storagedevice 150 may include a mass storage, removable storage, a volatileread-and-write memory, a read-only memory (ROM), or the like, or anycombination thereof. Exemplary mass storage may include a magnetic disk,an optical disk, a solid-state drive, etc. Exemplary removable storagemay include a flash drive, a floppy disk, an optical disk, a memorycard, a zip disk, a magnetic tape, etc. Exemplary volatileread-and-write memory may include a random-access memory (RAM).Exemplary RAM may include a dynamic RAM (DRAM), a double date ratesynchronous dynamic RAM (DDR SDRAM), a static RAM (SRAM), a thyristorRAM (T-RAM), and a zero-capacitor RAM (Z-RAM), etc. Exemplary ROM mayinclude a mask ROM (MROM), a programmable ROM (PROM), an erasableprogrammable ROM (PEROM), an electrically erasable programmable ROM(EEPROM), a compact disk ROM (CD-ROM), and a digital versatile disk ROM,etc. In some embodiments, the storage device 150 may be implemented on acloud platform. Merely by way of example, the cloud platform may includea private cloud, a public cloud, a hybrid cloud, a community cloud, adistributed cloud, an inter-cloud, a multi-cloud, or the like, or anycombination thereof.

In some embodiments, the storage device 150 may be connected to thenetwork 120 to communicate with one or more components of the MRI system100 (e.g., the terminal 130, the processing device 140). One or morecomponents of the MRI system 100 may access the data or instructionsstored in the storage device 150 via the network 120. In someembodiments, the storage device 150 may be directly connected to orcommunicate with one or more components of the MRI system 100 (e.g., theterminal 130, the processing device 140). In some embodiments, thestorage device 150 may be part of the processing device 140.

FIG. 2 is a schematic diagram illustrating exemplary hardware and/orsoftware components of a computing device on which the processing device140 may be implemented according to some embodiments of the presentdisclosure. As illustrated in FIG. 2, the computing device 200 mayinclude a processor 210, a storage 220, an input/output (I/O) 230, and acommunication port 240.

The processor 210 may execute computer instructions (program code) and,when executing the instructions, cause the processing device 140 toperform functions of the processing device 140 in accordance withtechniques described herein. The computer instructions may include, forexample, routines, programs, objects, components, signals, datastructures, procedures, modules, and functions, which perform particularfunctions described herein. In some embodiments, the processor 210 mayprocess data and/or images obtained from the MRI scanner 110, theterminal 130, the storage device 150, and/or any other component of theMRI system 100. For example, the processor 210 may cause an input signalprocessing module to process an input signal into at least two signals.A first signal of the at least two signals may be used for signaldetection, and a second signal of the at least two signals may be usedfor signal amplification. In some embodiments, the processor 210 mayinclude one or more hardware processors, such as a microcontroller, amicroprocessor, a reduced instruction set computer (RISC), anapplication specific integrated circuits (ASICs), anapplication-specific instruction-set processor (ASIP), a centralprocessing unit (CPU), a graphics processing unit (GPU), a physicsprocessing unit (PPU), a microcontroller unit, a digital signalprocessor (DSP), a field programmable gate array (FPGA), an advancedRISC machine (ARM), a programmable logic device (PLD), any circuit orprocessor capable of executing one or more functions, or the like, orany combinations thereof.

Merely for illustration, only one processor is described in thecomputing device 200. However, it should be noted that the computingdevice 200 in the present disclosure may also include multipleprocessors. Thus operations and/or method steps that are performed byone processor as described in the present disclosure may also be jointlyor separately performed by the multiple processors. For example, if inthe present disclosure the processor of the computing device 200executes both process A and process B, it should be understood thatprocess A and process B may also be performed by two or more differentprocessors jointly or separately in the computing device 200 (e.g., afirst processor executes process A and a second processor executesprocess B, or the first and second processors jointly execute processesA and B).

The storage 220 may store data/information obtained from the MRI scanner110, the terminal 130, the storage device 150, or any other component ofthe MRI system 100. In some embodiments, the storage 220 may include amass storage device, removable storage device, a volatile read-and-writememory, a read-only memory (ROM), or the like, or any combinationthereof. For example, the mass storage may include a magnetic disk, anoptical disk, a solid-state drive, etc. The removable storage mayinclude a flash drive, a floppy disk, an optical disk, a memory card, azip disk, a magnetic tape, etc. The volatile read-and-write memory mayinclude a random access memory (RAM). The RAM may include a dynamic RAM(DRAM), a double date rate synchronous dynamic RAM (DDR SDRAM), a staticRAM (SRAM), a thyristor RAM (T-RAM), and a zero-capacitor RAM (Z-RAM),etc. The ROM may include a mask ROM (MROM), a programmable ROM (PROM),an erasable programmable ROM (PEROM), an electrically erasableprogrammable ROM (EEPROM), a compact disk ROM (CD-ROM), and a digitalversatile disk ROM, etc. In some embodiments, the storage 220 may storeone or more programs and/or instructions to perform exemplary methodsdescribed in the present disclosure.

The I/O 230 may input or output signals, data, and/or information. Insome embodiments, the I/O 230 may enable a user interaction with theprocessing device 140. In some embodiments, the I/O 230 may include aninput device and an output device. Exemplary input devices may include akeyboard, a mouse, a touch screen, a microphone, or the like, or acombination thereof. Exemplary output devices may include a displaydevice, a loudspeaker, a printer, a projector, or the like, or acombination thereof. Exemplary display devices may include a liquidcrystal display (LCD), a light-emitting diode (LED)-based display, aflat panel display, a curved screen, a television device, a cathode raytube (CRT), or the like, or a combination thereof.

The communication port 240 may be connected to a network (e.g., thenetwork 120) to facilitate data communications. The communication port240 may establish connections between the processing device 140 and theMRI scanner 110, the terminal 130, or the storage device 150. Theconnection may be a wired connection, a wireless connection, or acombination of both that enables data transmission and reception. Thewired connection may include an electrical cable, an optical cable, atelephone wire, or the like, or any combination thereof. The wirelessconnection may include Bluetooth, Wi-Fi, WiMAX, WLAN, ZigBee, mobilenetwork (e.g., 3G, 4G, 5G, etc.), or the like, or a combination thereof.In some embodiments, the communication port 240 may be a standardizedcommunication port, such as RS232, RS485, etc. In some embodiments, thecommunication port 240 may be a specially designed communication port.For example, the communication port 240 may be designed in accordancewith the digital imaging and communications in medicine (DICOM)protocol.

FIG. 3 is a schematic diagram illustrating exemplary hardware and/orsoftware components of a mobile device according to some embodiments ofthe present disclosure. As illustrated in FIG. 3, the mobile device 300may include a communication platform 310, a display 320, a graphicsprocessing unit (GPU) 330, a central processing unit (CPU) 340, an I/O350, a memory 360, and a storage 390. In some embodiments, any othersuitable component, including but not limited to a system bus or acontroller (not shown), may also be included in the mobile device 300.In some embodiments, a mobile operating system 370 (e.g., iOS, Android,Windows Phone, etc.) and one or more applications 380 may be loaded intothe memory 360 from the storage 390 in order to be executed by the CPU340. The applications 380 may include a browser or any other suitablemobile apps for receiving and rendering information relating to imageprocessing or other information from the processing device 140. Userinteractions with the information stream may be achieved via the I/O 350and provided to the processing device 140 and/or other components of theMRI system 100 via the network 120.

To implement various modules, units, and their functionalities describedin the present disclosure, computer hardware platforms may be used asthe hardware platform(s) for one or more of the elements describedherein. The hardware elements, operating systems and programminglanguages of such computers are conventional in nature, and it ispresumed that those skilled in the art are adequately familiar therewithto adapt those technologies to the RFPA control device as describedherein. A computer with user interface elements may be used to implementa personal computer (PC) or another type of work station or terminaldevice, although a computer may also act as a server if appropriatelyprogrammed. It is believed that those skilled in the art are familiarwith the structure, programming and general operation of such computerequipment and as a result, the drawings should be self-explanatory.

FIG. 4A is a schematic diagram illustrating an exemplary radio frequencypower amplifier (RFPA) control device 405 according to some embodimentsof the present disclosure. FIG. 4B is a schematic diagram illustratingan exemplary radio frequency power amplifier (RFPA) 400 according tosome embodiments of the present disclosure. The RFPA 400 may include aRFPA control device (e.g., the RFPA control device 405 as illustrated inFIG. 4A), a radio frequency power amplification module 450, and a load460. The RFPA control device 405 may be configured to adjust an inputsignal to implement a nonlinear correction of the radio frequency poweramplification module 450. The radio frequency power amplification module450 may be configured to amplify the adjusted input signal and generatean output signal. In some embodiments, an amplification function (whichis nonlinear) of the radio frequency power amplification module 450 maybe pre-determined via tests. Then a correction function may bedetermined based on the amplification function. The RFPA control device405 may adjust the input signal according to the correction function.Then the radio frequency power amplification module 450 may amplify theadjusted input signal to generate the output signal that satisfiesuser's demand. The output signal may be transmitted to the load 460(e.g., RF coils). Unless otherwise stated, like reference numerals inFIGS. 4A and 4B refer to like components having the same or similarfunctions.

As shown in FIGS. 4A and 4B, the RFPA control device 405 may include aninput signal processing module 410, an adjustment module 430, and asignal processing and control module 440. The adjustment module 430 maybe connected to the input signal processing module 410 and the radiofrequency power amplification module 450, respectively. Specifically,the first end of the adjustment module 430 may be connected to the inputsignal processing module 410, and the second end of the adjustmentmodule 430 may be connected to the radio frequency power amplificationmodule 450. The signal processing and control module 440 may beconnected to the input signal processing module 410 and the adjustmentmodule 430, respectively. Specifically, the first end of the signalprocessing and control module 440 may be connected to the input signalprocessing module 410, and the second end of the signal processing andcontrol module 440 may be connected to the adjustment module 430. TheRFPA control device 400 may also include a delay module 420. The delaymodule 420 may be disposed between the input signal processing module410 and the adjustment module 430.

The input signal processing module 410 may be configured to process aninput signal into at least two signals. A first signal (also referred toas first input signal) of the at least two signals may be used forsignal detection, and a second signal (also referred to as second inputsignal) of the at least two signals may be used for signalamplification. In some embodiments, the input signal processing module410 may be a power divider, a couper, or the like, or a combinationthereof. The power divider may divide the input signal into two equal orunequal signals (i.e., the first signal, the second signal). The coupermay extract a portion of signal from the input signal as the firstsignal, and the remaining signal as the second signal. In someembodiments, the first signal may be transmitted to the signalprocessing and control module 440. The second signal may be transmittedto the delay module 420.

The signal processing and control module 440 may be configured togenerate a control signal based on at least one feature of the firstsignal. The control signal may be used to control a degree of theadjustment of the at least one feature of the second signal. In someembodiments, the at least one feature of the first signal may includeamplitude, phase, or the like, or any combination thereof. In someembodiments, the signal processing and control module 440 may includeone or more sub-modules (such as an input signal detection sub-module, asignal processing and control sub-module, an output signal detectionsub-module) configured to determine the control signal. Moredescriptions of the sub-modules may be found elsewhere in the presentdisclosure (e.g., FIGS. 5A, 5B, 6A, and 6B, and the descriptionsthereof).

The adjustment module 430 may be configured to adjust at least onefeature of the second signal. In some embodiments, the at least onefeature of the second signal may include amplitude, phase, or the like,or any combination thereof. The adjustment module 430 may include acontrollable attenuator, a phase shifter, or the like. The controllableattenuator may be used to adjust the amplitude of the second signal. Thephase shifter may be used to adjust the phase of the second signal. Insome embodiments, the adjustment module 430 may transmit the adjustedsecond signal into the radio frequency power amplification module 450for amplification. For example, the radio frequency power amplificationmodule 450 may amplify the amplitude of the adjusted second signaland/or adjust the phase of the second signal to generate the outputsignal.

As shown in FIG. 4B, the first signal may be transmitted to the signalprocessing and control module 440 and processed by the signal processingand control module 440 to generate the control signal. The controlsignal may then be transmitted to the adjustment module 430. In someembodiments, the generation of the control signal may take a certainamount of time, while the second signal may be directly transmitted tothe adjustment module 430. Thus, the moment that the control signalreaches the adjustment module 430 may be significantly later than themoment that the second signal reaches the adjustment module 430, whichmay result in poor nonlinear correction effects of the radio frequencypower amplification module 450 (especially for fast response signals),and further may cause imaging artifacts in an MRI system (e.g., the MRIsystem 100). Thus, the delay module 420 may be disposed between theinput signal processing module 410 and the adjustment module 430 todelay the moment that the second signal reaches the adjustment module430.

The delay module 420 may be configured to determine a delay of thesecond signal such that the second signal and the control signal mayroughly simultaneously reach the adjustment module 430. As used herein,“roughly simultaneously reaching” refers to a time difference betweenthe moment that the second signal reaches the adjustment module 430 andthe moment that the control signal reaches the adjustment module 430 isless than several nanoseconds (e.g., 10 nanoseconds, 20 nanoseconds, 50nanoseconds). The delay module 420 is configured to delay the time whenthe inputted to-be-amplified signal reaches the adjustment module 430.For example, the delay module 420 may adjust a time difference betweenthe moment that the second signal reaches the adjustment module 430 andthe moment that the control signal reaches the adjustment module 430. Insome embodiments, the time difference may be 0. In this case, the secondsignal and the control signal may simultaneously reach the adjustmentmodule 430. Alternatively, the time difference may be severalnanoseconds, several microseconds, or the like. In this case, the secondsignal and the control signal may be regarded as approximatelysimultaneously reaching the adjustment module 430. The delay module 420may include a LC filter, a surface acoustic wave filter (SAWF), a delayline, or the like, or any combination thereof. The delay time may bedetermined when the delay module 420 may be fabricated. In someembodiments, a plurality of delay modules with different delay times maybe fabricated according to actual demands.

In some embodiments of the present disclosure, the delay module 420 maybe disposed between the input signal processing module 410 and theadjustment module 430 to delay the transmission of the second signal,which may counteract the time difference between the moment that thecontrol signal reaches the adjustment module 430 and the moment that thesecond signal reaches the adjustment module 430, thus achieving goodnonlinear correction effects and further avoiding imaging artifacts inan MRI system (e.g., the MRI system 100).

It should be noted that the above description is merely provided for thepurposes of illustration, and not intended to limit the scope of thepresent disclosure. For persons having ordinary skills in the art,multiple variations and modifications may be made under the teachings ofthe present disclosure. However, those variations and modifications donot depart from the scope of the present disclosure. In someembodiments, the RFPA may be applied to an MRI system (e.g., the MRIsystem 100). Alternatively or additionally, the RFPA may be used invarious applications, such as broadcasting, satellite communications,cellular communications, or the like.

FIG. 5A is a schematic diagram illustrating an exemplary radio frequencypower amplifier (RFPA) control device 505 according to some embodimentsof the present disclosure. FIG. 5B is a schematic diagram illustratingan exemplary radio frequency power amplifier (RFPA) 500 according tosome embodiments of the present disclosure. The RFPA 500 may include aRFPA control device (e.g., the RFPA control device 505 as illustrated inFIG. 5A), a radio frequency power amplification module 550, and a load560. The RFPA control device 505 may be configured to adjust an inputsignal to implement a nonlinear correction of the radio frequency poweramplification module 550. The radio frequency power amplification module550 may be configured to amplify the adjusted input signal and generatean output signal. The output signal may be transmitted to the load 560(e.g., RF coils). Unless otherwise stated, like reference numerals inFIGS. 5A and 5B refer to like components having the same or similarfunctions.

As shown in FIGS. 5A and 5B, the RFPA control device 505 may include aninput signal processing module 510, a delay module 520, an adjustmentmodule 530, and a signal processing and a control module 540. Theconnection of the modules of the RFPA control device 505 may be the sameas the modules of the RFPA control device 405. The functions of theinput signal processing module 510, the delay module 520, the adjustmentmodule 530, and the signal processing and control module 540 may be thesame as or similar to the functions of the input signal processingmodule 410, the delay module 420, the adjustment module 430, and thesignal processing and control module 440, and the relevant descriptionsare not repeated herein.

As shown in FIGS. 5A and 5B, the signal processing and control module540 may further include an input signal detection sub-module 542 and asignal processing and control sub-module 544. The input signal detectionsub-module 542 may be connected to the input signal processing module510. The signal processing and control sub-module 544 may include afirst end 544 a and a second end 544 b. The first end 544 a may beconnected to the input signal detection sub-module 542. The second end544 b may be connected to the adjustment module 530.

The input signal detection sub-module 542 may be configured to detectthe at least one feature of the first signal. The at least one featureof the first signal may include amplitude, phase, or the like. In someembodiments, the at least one feature may only include amplitude.Alternatively, the at least one feature may only include phase.Alternatively, the at least one feature may include amplitude and phase.The input signal detection sub-module 542 may detect the amplitudeand/or phase of the first signal, and transmit the detected amplitudeand/or detected phase of the first signal into the signal processing andcontrol sub-module 544.

In some embodiments, the input signal detection sub-module 542 may be adevice configured to detect the at least one feature of the firstsignal. The input signal detection sub-module 542 may include adetector, a diode, a phase discriminator, or the like, or anycombination thereof. For example, the detector may be used to detect theamplitude of the first signal. The phase discriminator may be used todetect the phase of the first signal. In some embodiments, the inputsignal detection sub-module 542 may be a signal detection circuit. Forexample, the at least one feature of the first signal may include theamplitude of the first signal. The signal detection circuit may detectthe at least one feature (i.e., the amplitude) of the first signal via aenvelope-demodulation. As another example, the at least one feature ofthe first signal may include the phase of the first signal. The signaldetection circuit may detect the at least one feature (i.e., the phase)of the first signal via a direct radio frequency sampling.

The signal processing and control sub-module 544 may be configured togenerate the control signal based on the at least one feature of thefirst signal. The control signal may be used to control the degree ofthe adjustment of the at least one feature of the second signal. In someembodiments, the signal processing and control sub-module 544 maydetermine the amplitude of the input signal based on the amplitude ofthe first signal. The signal processing and control sub-module 544 maydetermine the degree of the adjustment of the amplitude of the secondsignal based on the amplitude of the input signal and user's demand(e.g., a required amplitude of the output signal outputted by the radiofrequency power amplification module 550). For example, theamplification function of the radio frequency power amplification module550 may be determinate. To obtain the required amplitude of the outputsignal, a correction function may be determined based on theamplification function. The degree of the adjustment of the amplitude ofthe second signal may be determined based on the amplitude of the inputsignal and the correction function. In some embodiments, the degree ofthe adjustment of the phase of the second signal may be determined basedon the degree of the adjustment of the amplitude of the second signal.The signal processing and control sub-module 544 may determine thedegree of the adjustment of the phase of the second signal based on thedegree of the adjustment of the amplitude of the second signal. Thus,the signal processing and control sub-module 544 may generate thecontrol signal based on the degree of adjustment of the amplitude and/orphase of the second signal.

The control signal may be applied to the adjustment module 530, andconfigured to control the degree of adjustment of the amplitude and/orphase of the second signal. The amplitude and/or phase of the secondsignal may be adjusted by the adjustment module 530, and further beamplified by the radio frequency power amplification module 550 togenerate a required output signal. In the present disclosure, before theradio frequency power amplification module 550 amplifies the secondsignal (e.g., before amplifying the amplitude and/or phase of the secondsignal), the adjustment module 530 may adjust and/or correct (e.g.,nonlinearly correct) the second signal (e.g., the amplitude and/or phaseof the second signal) to ensure that the output signal (e.g., theamplitude and/or phase of the output signal) satisfies user's demands.In some embodiments, the second signal is relatively small before theamplification, and thus, it is easy to achieve the adjustment andcorrection.

In some embodiments, the delay module 520 may adjust a time differencebetween the moment that the second signal reaches the adjustment module530 and the moment that the control signal reaches the adjustment module530. In some embodiments, the time difference may be 0, severalnanoseconds (e.g., 5 nanoseconds, 10 nanoseconds), several microseconds(e.g., 0.01 microsecond, 0.05 microseconds), or the like. When the timedifference is 0, the control signal and the second signal maysimultaneously reach the adjustment module 530. When the time differenceis 0.05 microseconds, the control signal and the second signal mayapproximately simultaneously reach the adjustment module 530, and theimaging stability (e.g., whether there is an image artifact) of the MRIsystem 100 may not affected by the slightly time difference. In thepresent disclosure, by introducing the delay module 530 into the RFPAcontrol device 505, it may compensate for the time difference that thecontrol signal lags behind the second signal, thereby avoiding poorimaging stability (or even image artifact) of the MRI system 100.

In some embodiments, the delay time of the delay module 520 may be apredetermined value to delay the moment that the second signal reachesthe adjustment module 530. The delay of the second signal may be greaterthan 0.2 microseconds. Specifically, the delay of the second signal maybe 0.4 microseconds, 0.5 microseconds, 0.7 microseconds, 1 microsecond,or the like.

In some embodiments, a total transmission time from a moment that thefirst signal is transmitted to the signal processing and control module540 to a moment that the control signal is transmitted to the adjustmentmodule 530 may be composed of four transmission times, that is, a firsttransmission time, a second transmission time, a third transmissiontime, and a fourth transmission time.

In some embodiments, the first transmission time may be a time that theinput signal detection sub-module 542 detects the at least one featureof the first signal. The second transmission time may be a time that thesignal processing and control sub-module 544 processes the first signaland generates the control signal. The third transmission time may be atime of transmitting the control signal to the adjustment module 530.The fourth transmission time may be an adjustable delay time imposed byan adjustable delay unit of the signal processing and controlsub-module.

In some embodiments, the transmission link of the second signal (i.e.,the input signal processing module 510—the delay module 520—theadjustment module 530—the radio frequency power amplification module550) may be a radio frequency (RF) transmission link. The delay module520 may be a LC filter, a surface acoustic wave filter (SAWF), a delayline, or the like, or any combination thereof. The delay time may bedetermined when the delay module 520 is fabricated. Due to the radiofrequency transmission link, the delay module 520 may provide an RFdelay, which is a fixed value and cannot be changed in real-time.Therefore, the delay has to be preset, resulting in inaccurate delaywhich further leads to the time difference between the moment that thesecond signal reaches the adjustment module 530 and the moment that thecontrol signal reaches the adjustment module 530 is undesirablyexcessively large or small.

In some embodiments, the total transmission time from a moment that thefirst signal is transmitted to the signal processing and control module540 to a moment that the control signal is transmitted to the adjustmentmodule 530 may be varied due to the situations described above. Forexample, for the first signals with different amplitudes or phases, thesecond times (i.e., a time that the signal processing and controlsub-module 544 processes the first signal and generates the controlsignal) may be different.

In order to ensure that the control signal and the second signal roughlysimultaneously reach the adjustment module 530, the signal processingand control sub-module 544 may include the adjustable delay unit. Insome embodiments, the transmission link of the control signal may belongto a analog domain or a digital domain. A delay on the analog domain orthe digital domain may be adjustable. The adjustable delay unit may beconfigured to impose an adjustable delay on the control signal to adjustthe moment that the control signal reaches the adjustment module 530. Insome embodiments, the adjustable delay imposed on the control signal maybe the fourth transmission time. The adjustable delay unit may cooperatewith the delay module 520 to ensure that the control signal and thesecond signal roughly simultaneously reach the adjustment module 530.

In some embodiments, the adjustable delay unit may adjust the fourthtransmission time to change a time difference between the totaltransmission time and the delay of the second signal such that thesecond signal and the control signal roughly simultaneously reach theadjustment module. For example, the time difference between the totaltransmission time and the delay of the second signal may be expressed asEquation (1) as below:T _(s) =T−T ₀ =T−(T ₁ +T ₂ +T ₃ +T ₄),  (1)wherein T_(s) refers to the time difference between total transmissiontime and the delay of the second signal (or the time difference betweenthe moment that the second signal reaches the adjustment module 530 andthe moment that the control signal reaches the adjustment module 530); Trefers to delay of the second signal; T₀ refers to the totaltransmission time; T₁ refers to the first transmission time; T₂ refersto the second transmission time; T₃ refers to the third transmissiontime; and T₄ refers to the fourth transmission time.

Merely by way of example, if the delay of the second signal is equal tothe total transmission time (i.e., a sum of the first transmission time,the second transmission time, the third transmission time, and thefourth transmission time), the time difference between the moment thatthe second signal reaches the adjustment module 530 and the moment thatthe control signal reaches the adjustment module 530 may be 0, that is,T_(s)=0.

In the present disclosure, by adjusting the fourth transmission time bythe adjustable delay unit, the time difference between the moment thatthe second signal reaches the adjustment module 530 and the moment thatthe control signal reaches the adjustment module 530 may be changed suchthat the second signal and the control signal may roughly simultaneouslyreach the adjustment module 530, which may improve the imaging stabilityof the MRI system 100 and avoid image artifacts.

FIG. 6A is a schematic diagram illustrating an exemplary radio frequencypower amplifier (RFPA) control device 605 according to some embodimentsof the present disclosure. FIGS. 6B and 6C are schematic diagramsillustrating an exemplary radio frequency power amplifier (RFPA)according to some embodiments of the present disclosure. The RFPA 600 asillustrated in FIG. 6B may include a RFPA control device (e.g., the RFPAcontrol device 605 as illustrated in FIG. 6A), a radio frequency poweramplification module 650, and a load 660. The RFPA 600′ as illustratedin FIG. 6C may include a RFPA control device (e.g., the RFPA controldevice 605 as illustrated in FIG. 6A), and a radio frequency poweramplification module 650. The RFPA control device 605 may be configuredto adjust an input signal to implement a nonlinear correction of theradio frequency power amplification module 650. The radio frequencypower amplification module 650 may be configured to amplify the adjustedinput signal and generate an output signal. The output signal may betransmitted to the load 660 (e.g., RF coils). Unless otherwise stated,like reference numerals in FIGS. 6A-6C refer to like components havingthe same or similar functions.

As shown in FIGS. 6A-6C, the RFPA control device 605 may include aninput signal processing module 610, a delay module 620, an adjustmentmodule 630, and a signal processing and a control module 640. Theconnection of the modules of the RFPA control device 605 may be the sameas the modules of the RFPA control device 405. The functions of theinput signal processing module 610, the delay module 620, the adjustmentmodule 630, and the signal processing and control module 640 may be thesame as or similar to the functions of the input signal processingmodule 410, the delay module 420, the adjustment module 430, and thesignal processing and control module 440, and the descriptions are notrepeated herein.

As described in connection with FIGS. 5A and 5B, the signal processingand control module 640 may detect the at least one feature of the firstsignal, and generate the control signal based on the feature of thefirst signal and the feature of the output radio frequency signaldesired by the user (e.g., the feature of a required output signal). Theadjustment module 630 may adjust the at least one feature of the secondsignal based on the control signal, and the radio frequency poweramplification module 650 may further amplify the at least one feature ofthe second signal to generate the output signal. However, in some cases,the actual output signal generated by the radio frequency poweramplification module 650 may be different from the required outputsignal (e.g., a small error exists). That is, the detection of the firstsignal alone may not achieve the accurate nonlinear correction of theradio frequency power amplification module 650. In some embodiments, toeliminate the small error between the actual output signal and therequired output signal, the output radio frequency signal (i.e., theactual output signal) needs to be processed further by an output signalprocessing module 670, and accordingly, the control signal may beadjusted based on the processed output signal.

In some embodiments, the RFPA control device 605 may further include theoutput signal processing module 670. The output signal processing module670 may be connected to the radio frequency power amplification module650. The output signal processing module 670 may be configured toprocess the output signal (i.e., the actual output signal) into at leasttwo output signals. A first output signal of the at least two outputsignals may be used for signal detection, and a second output signal ofthe at least two output signals may be transmitted to the load 660. Insome embodiments, the first output signal may be used to adjust thecontrol signal.

As shown in FIG. 6A, the signal processing and control module 640 mayinclude an input signal detection sub-module 642, a signal processingand control sub-module 644, and an output signal detection sub-module646. The input signal detection sub-module 642 may be connected to theinput signal processing module 610. The output signal detectionsub-module 646 may be connected to the output signal processing module670. The signal processing and control sub-module 644 may include afirst end 644 a, a second end 644 b, and a third end 644 c. The firstend 644 a may be connected to the input signal detection sub-module 642.The second end 644 b may be connected to the adjustment module 630. Thethird end 644 c may be connected to the output signal detectionsub-module 646.

In some embodiments, the input signal detection sub-module 642 may beconfigured to detect the at least one feature of the first signal (alsoreferred to as first input signal) and transmit the first signal to thesignal processing and control sub-module 644. The output signaldetection sub-module 646 may be configured to detect at least onefeature of the first output signal and transmit the first output signalto the signal processing and control sub-module 644. The signalprocessing and control sub-module 644 may determine the control signalbased on the at least one feature of the first signal and the at leastone feature of the first output signal. For example, the signalprocessing and control sub-module 644 may adjust the control signalbased on an error between the at least one feature of the first signaland the at least one feature of the first output signal. The controlsignal may be used to control the degree of the adjustment of the atleast one feature of the second signal.

The at least one feature of the first signal and/or the first outputsignal may include amplitude, phase, or the like, or any combinationthereof. In some embodiments, the signal processing and controlsub-module 644 may determine the amplitude of the input signal based onthe amplitude of the first signal. The signal processing and controlsub-module 644 may determine the amplitude of the output signal based onthe amplitude of the first output signal. The signal processing andcontrol sub-module 644 may determine the degree of the adjustment of theamplitude of the second signal based on the amplitude of the inputsignal, the amplitude of the actual output signal, and the user's demand(e.g., the amplitude of the required output signal). The signalprocessing and control sub-module 644 may determine the degree of theadjustment of the phase of the second signal based on the degree of theadjustment of the amplitude of the second signal. Thus, the signalprocessing and control sub-module 644 may generate the control signalbased on the degree of adjustment of the amplitude and/or phase of thesecond signal. When the RFPA control device 605 works, the signalprocessing and control sub-module 644 may continually adjust the controlsignal based on the input signal (e.g., the first signal), the actualoutput signal (e.g., the first output signal), and the user's demand(e.g., the output signal required by the user). And the signalprocessing and control sub-module 644 may continually adjust the secondsignal based on the control signal until the required output signal isobtained.

In some embodiments of the present disclosure, the control signal may bedetermined or adjusted based on the feature(s) of the input signal andthe feature(s) of the actual output signal. The second signal may beadjusted based on the control signal, and further be amplified by theradio frequency power amplification module 650 to generate the requiredoutput signal. The above process may form a closed-loop control, whichmay implement the precise nonlinear correction of the radio frequencypower amplification module 650.

FIG. 7 is a flowchart illustrating an exemplary process for adjusting asecond signal according to some embodiments of the present disclosure.For illustration purposes only, the processing device 140 may bedescribed as a subject to perform the process 700. However, one ofordinary skill in the art would understand that the process 700 may alsobe performed by other entities. In some embodiments, one or moreoperations of process 700 may be implemented in the MRI system 100illustrated in FIG. 1. For example, the process 700 may be stored in thestorage device 150 and/or the storage 220 in the form of instructions(e.g., an application), and invoked and/or executed by one or morecomponents of the RFPA 405 (or 505, 605) as illustrated in FIG. 4A (orFIG. 5A, FIG. 6A). The operations of the illustrated process presentedbelow are intended to be illustrative. In some embodiments, the process700 may be accomplished with one or more additional operations notdescribed, and/or without one or more of the operations discussed.Additionally, the order in which the operations of the process 700 asillustrated in FIG. 7A and described below is not intended to belimiting.

In 701, the processing device 140 (e.g., the input signal processingmodule 410, the input signal processing module 510, the input signalprocessing module 610) may process an input signal into at least twosignals. The processing device 140 may divide the input signal into twoequal signals, or two unequal signals. A first signal of the at leasttwo signals may be transmitted to a signal processing and control module(e.g., the signal processing and control module 440, the signalprocessing and control module 540, the signal processing and controlmodule 640) and used for signal detection. A second signal of the atleast two signals may be transmitted to a delay module (e.g., the delaymodule 420, the delay module 520, the delay module 620) and used forsignal amplification.

In 703, the processing device 140 (e.g., the signal processing andcontrol module 440, the signal processing and control module 540, thesignal processing and control module 640) may generate a control signalbased on at least feature of the first signal. The control signal may beused to control a degree of the adjustment of at least one feature ofthe second signal.

In some embodiments, the processing device 140 may detect the at leastone feature of the first signal. The at least one feature of the firstsignal may include amplitude, phase, or the like, or any combinationthereof. In some embodiments, the processing device 140 may detect theamplitude of the first signal via a envelope-demodulation. Theprocessing device 140 may detect the phase of the first signal via adirect radio frequency sampling. The processing device 140 may generatethe control signal based on the at least one feature of the firstsignal. Specifically, the processing device 140 may determine theamplitude of the input signal based on the amplitude of the firstsignal. The processing device 140 may determine the degree of theadjustment of the amplitude of the second signal based on the amplitudeof the input signal and the amplitude of the output signal desired bythe user (e.g., a required output signal). The processing device 140 mayalso determine the degree of the adjustment of the phase of the secondsignal based on the degree of the adjustment of the phase of the secondsignal. Thus, the processing device 140 may determine the control signalbased on the degree of the adjustment of the amplitude and/or phase ofthe second signal.

In 705, the processing device 140 (e.g., the delay module 420, the delaymodule 520, the delay module 620) may determine a delay of the secondsignal such that the second signal and the control signal roughlysimultaneously reach an adjustment module (e.g., the adjustment module430, the adjustment module 530, the adjustment module 630). In someembodiments, the processing device 140 may adjust a time differencebetween the moment that the second signal reaches the adjustment moduleand the moment that the control signal reaches the adjustment module. Insome embodiments, the time difference may be 0, several nanoseconds (2nanoseconds, 5 nanoseconds, 10 nanoseconds), or several microseconds(e.g., 0.01 microseconds, 0.05 microseconds), or the like. Moredescriptions of the determination of the delay of the second signal maybe found elsewhere in the present disclosure (e.g., FIGS. 5A and 5B andthe relevant descriptions thereof).

In 707, the processing device 140 (e.g., the adjustment module 430, theadjustment module 530, the adjustment module 630) may adjust at leastone feature of the second signal based on the control signal. The atleast one feature of the second signal may include amplitude, phase, orthe like, or any combination thereof. In some embodiments, theprocessing device 140 may adjust the amplitude of the second signal.Alternatively, the processing device 140 may adjust the phase of thesecond signal. Alternatively, the processing device 140 may adjust theamplitude and the phase of the second signal.

In some embodiments, the processing device 140 (e.g., the radiofrequency power amplification module 450, the radio frequency poweramplification module 550, the radio frequency power amplification module650) may amplify the adjusted second signal to generate an outputsignal. In some embodiments, the processing device 140 (e.g., the outputsignal processing module 670) may process the output signal into atleast two output signals. A first output signal of the at least twooutput signals may be used for signal detection, and a second outputsignal of the at least two output signals may be transmitted to a load(e.g., RF coils). In some embodiments, the first output signal may beused to adjust the control signal. For example, the processing device140 may detect at least one feature of the first output signal. The atleast one feature of the first output signal may include amplitude,phase, or the like, or any combination thereof. The processing device140 may determine the control signal based on the at least one featureof the first signal and the at least one feature of the first outputsignal.

It should be noted that the above description is merely provided for thepurposes of illustration, and not intended to limit the scope of thepresent disclosure. For persons having ordinary skills in the art,multiple variations and modifications may be made under the teachings ofthe present disclosure. However, those variations and modifications donot depart from the scope of the present disclosure. For example,operations 703 and 705 may be performed simultaneously. As anotherexample, operation 705 may be performed before operation 703.

Having thus described the basic concepts, it may be rather apparent tothose skilled in the art after reading this detailed disclosure that theforegoing detailed disclosure is intended to be presented by way ofexample only and is not limiting. Various alterations, improvements, andmodifications may occur and are intended to those skilled in the art,though not expressly stated herein. These alterations, improvements, andmodifications are intended to be suggested by this disclosure, and arewithin the spirit and scope of the exemplary embodiments of thisdisclosure.

Moreover, certain terminology has been used to describe embodiments ofthe present disclosure. For example, the terms “one embodiment,” “anembodiment,” and/or “some embodiments” mean that a particular feature,structure or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure.Therefore, it is emphasized and should be appreciated that two or morereferences to “an embodiment” or “one embodiment” or “an alternativeembodiment” in various portions of this specification are notnecessarily all referring to the same embodiment. Furthermore, theparticular features, structures or characteristics may be combined assuitable in one or more embodiments of the present disclosure.

Further, it will be appreciated by one skilled in the art, aspects ofthe present disclosure may be illustrated and described herein in any ofa number of patentable classes or context including any new and usefulprocess, machine, manufacture, or composition of matter, or any new anduseful improvement thereof. Accordingly, aspects of the presentdisclosure may be implemented entirely hardware, entirely software(including firmware, resident software, micro-code, etc.) or combiningsoftware and hardware implementation that may all generally be referredto herein as a “unit,” “module,” or “system.” Furthermore, aspects ofthe present disclosure may take the form of a computer program productembodied in one or more computer readable media having computer readableprogram code embodied thereon.

A non-transitory computer readable signal medium may include apropagated data signal with computer readable program code embodiedtherein, for example, in baseband or as part of a carrier wave. Such apropagated signal may take any of a variety of forms, includingelectro-magnetic, optical, or the like, or any suitable combinationthereof. A computer readable signal medium may be any computer readablemedium that is not a computer readable storage medium and that maycommunicate, propagate, or transport a program for use by or inconnection with an instruction execution system, apparatus, or device.Program code embodied on a computer readable signal medium may betransmitted using any appropriate medium, including wireless, wireline,optical fiber cable, RF, or the like, or any suitable combination of theforegoing.

Computer program code for carrying out operations for aspects of thepresent disclosure may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C #, VB.NET, Python or the like, conventional procedural programming languages,such as the “C” programming language, Visual Basic, Fortran 2003, Perl,COBOL 2002, PHP, ABAP, dynamic programming languages such as Python,Ruby and Groovy, or other programming languages. The program code mayexecute entirely on the user's computer, partly on the user's computer,as a stand-alone software package, partly on the user's computer andpartly on a remote computer or entirely on the remote computer orserver. In the latter scenario, the remote computer may be connected tothe user's computer through any type of network, including a local areanetwork (LAN) or a wide area network (WAN), or the connection may bemade to an external computer (for example, through the Internet using anInternet Service Provider) or in a cloud computing environment oroffered as a service such as a Software as a Service (SaaS).

Furthermore, the recited order of processing elements or sequences, orthe use of numbers, letters, or other designations therefore, is notintended to limit the claimed processes and methods to any order exceptas may be specified in the claims. Although the above disclosurediscusses through various examples what is currently considered to be avariety of useful embodiments of the disclosure, it is to be understoodthat such detail is solely for that purpose, and that the appendedclaims are not limited to the disclosed embodiments, but, on thecontrary, are intended to cover modifications and equivalentarrangements that are within the spirit and scope of the disclosedembodiments. For example, although the implementation of variouscomponents described above may be embodied in a hardware device, it mayalso be implemented as a software only solution, e.g., an installationon an existing server or mobile device.

Similarly, it should be appreciated that in the foregoing description ofembodiments of the present disclosure, various features are sometimesgrouped together in a single embodiment, figure, or description thereoffor the purpose of streamlining the disclosure aiding in theunderstanding of one or more of the various inventive embodiments. Thismethod of disclosure, however, is not to be interpreted as reflecting anintention that the claimed object matter requires more features than areexpressly recited in each claim. Rather, inventive embodiments lie inless than all features of a single foregoing disclosed embodiment.

In some embodiments, the numbers expressing quantities, properties, andso forth, used to describe and claim certain embodiments of theapplication are to be understood as being modified in some instances bythe term “about,” “approximate,” or “substantially.” For example,“about,” “approximate,” or “substantially” may indicate ±20% variationof the value it describes, unless otherwise stated. Accordingly, in someembodiments, the numerical parameters set forth in the writtendescription and attached claims are approximations that may varydepending upon the desired properties sought to be obtained by aparticular embodiment. In some embodiments, the numerical parametersshould be construed in light of the number of reported significantdigits and by applying ordinary rounding techniques. Notwithstandingthat the numerical ranges and parameters setting forth the broad scopeof some embodiments of the application are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspracticable.

Each of the patents, patent applications, publications of patentapplications, and other material, such as articles, books,specifications, publications, documents, things, and/or the like,referenced herein is hereby incorporated herein by this reference in itsentirety for all purposes, excepting any prosecution file historyassociated with same, any of same that is inconsistent with or inconflict with the present document, or any of same that may have alimiting affect as to the broadest scope of the claims now or laterassociated with the present document. By way of example, should there beany inconsistency or conflict between the description, definition,and/or the use of a term associated with any of the incorporatedmaterial and that associated with the present document, the description,definition, and/or the use of the term in the present document shallprevail.

In closing, it is to be understood that the embodiments of theapplication disclosed herein are illustrative of the principles of theembodiments of the application. Other modifications that may be employedmay be within the scope of the application. Thus, by way of example, butnot of limitation, alternative configurations of the embodiments of theapplication may be utilized in accordance with the teachings herein.Accordingly, embodiments of the present application are not limited tothat precisely as shown and described.

What is claimed is:
 1. A control device of a radio frequency poweramplifier in a magnetic-resonance imaging (MRI) system, coupled to aradio frequency power amplification module of the radio frequency poweramplifier via a signal connection, the control device comprising: aninput signal processing module, configured to process an MRI radiofrequency input signal into at least two signals, wherein a first signalof the at least two signals is used for signal detection, and a secondsignal of the at least two signals is used for signal amplification; asignal processing and control module, configured to receive the firstsignal and output a control signal, wherein the control signal controlsa degree of the adjustment of the second signal; an adjustment moduleconfigured to adjust, based on the control signal, an amplitude and/or aphase of the second signal; and a delay module comprising a surfaceacoustic wave filter, disposed between the input signal processingmodule and the adjustment module, configured to determine a delay of thesecond signal, wherein the signal processing and control module isfurther configured to impose an adjustable delay on the control signal,so as to cooperate with the delay module to ensure that the controlsignal and the second signal simultaneously reach the adjustment module.2. The control device of claim 1, wherein: the adjustment module isconnected to the input signal processing module and the radio frequencypower amplification module, respectively; and the signal processing andcontrol module is connected to the input signal processing module andthe adjustment module, respectively, configured to generate the controlsignal based on at least one feature of the first signal, wherein thecontrol signal is configured to control a degree of the adjustment ofthe at least one feature of the second signal.
 3. The control device ofclaim 2, wherein the signal processing and control module furthercomprises: an input signal detection sub-module, connected to the inputsignal processing module, configured to detect the at least one featureof the first signal; and a signal processing and control sub-module,connected to the input signal detection sub-module and the adjustmentmodule, respectively, configured to generate the control signal based onthe at least one feature of the detected first signal.
 4. The controldevice of claim 3, wherein the input signal detection sub-moduleincludes at least one of a detector, a diode, or a phase discriminator.5. The control device of claim 3, wherein a total transmission time froma moment that the first signal is transmitted to the signal processingand control module to a moment that the control signal is transmitted tothe adjustment module is composed of a first transmission time, a secondtransmission time, a third transmission time, and a fourth transmissiontime, wherein: the first transmission time is a time that the inputsignal detection sub-module detects the at least one feature of thefirst signal; the second transmission time is a time that the signalprocessing and control sub-module processes the first signal andgenerates the control signal; the third transmission time is a time oftransmitting the control signal to the adjustment module; and the fourthtransmission time is an adjustable delay time imposed by an adjustabledelay unit of the signal processing and control sub-module.
 6. Thecontrol device of claim 5, wherein the adjustable delay unit adjusts thefourth transmission time to change a time difference between the totaltransmission time and the delay of the second signal such that thesecond signal and the control signal roughly simultaneously reach theadjustment module.
 7. The control device of claim 2, wherein the atleast one feature of the first signal includes amplitude and/or phase.8. The control device of claim 2, wherein the radio frequency poweramplification module is configured to receive and amplify the adjustedsecond signal to generate an output signal.
 9. The control device ofclaim 8, further comprising an output signal processing module,connected to the radio frequency power amplification module, configuredto process the output signal into at least two output signals, wherein afirst output signal of the at least two output signals is used forsignal detection, and a second output signal of the at least two outputsignals is transmitted to a load.
 10. The control device of claim 9,wherein the signal processing and control module further includes anoutput signal detection sub-module, connected to a signal processing andcontrol sub-module of the signal processing and control module, whereinthe output signal detection sub-module is configured to detect at leastone feature of the first output signal; and the signal processing andcontrol sub-module is connected to the adjustment module and configuredto generate the control signal based on the at least one feature of thefirst signal and the at least one feature of the first output signal.11. The control device of claim 10, wherein the signal processing andcontrol sub-module is further configured to adjust the control signalbased on the amplitude of the first signal, the amplitude of the firstoutput signal, and a user's demand.
 12. The control device of claim 1,wherein the delay of the second signal is longer than 1 microsecond. 13.A method for controlling a radio frequency power amplifier in a magneticresonance imaging (MRI) system, implemented on a computing deviceincluding at least one processor, at least one storage device, and acommunication platform connected to a network, comprising: processing,by an input signal processing module, an MRI radio frequency inputsignal into at least two signals, wherein a first signal of the at leasttwo signals is used for signal detection, and a second signal of the atleast two signals is used for signal amplification; generating, by asignal processing and control module, a control signal based on at leastone feature of the first signal; determining, by a delay modulecomprising a surface acoustic wave filter, a delay of the second signal;and adjusting, by an adjustment module based on the control signal, anamplitude and/or a phase of the second signal; wherein the methodfurther comprises: imposing, by the signal processing and controlmodule, an adjustable delay on the control signal, so as to cooperatewith the delay module to ensure that the control signal and the secondsignal simultaneously reach the adjustment module.
 14. The method ofclaim 13, wherein the generating a control signal based on at least onefeature of the first signal comprises: detecting the at least onefeature of the first signal; and generating the control signal based onthe at least one feature of the detected first signal.
 15. The method ofclaim 13, further comprising: amplifying, by a radio frequency poweramplification module of the radio frequency power amplifier, theadjusted second signal to generate an output signal.
 16. The method ofclaim 15, further comprising: processing, by an output signal processingmodule, the output signal into at least two output signals, wherein afirst output signal of the at least two output signals is used forsignal detection, and a second output signal of the at least two outputsignals is transmitted to a load.
 17. The method of claim 16, whereinthe generating a control signal based on at least one feature of thefirst signal comprises: detecting at least one feature of the firstoutput signal; and generating the control signal based on the at leastone feature of the first signal and the at least one feature of thefirst output signal.
 18. A radio frequency power amplifier, comprising:a control device of the radio frequency power amplifier in amagnetic-resonance imaging (MRI) system, coupled to a radio frequencypower amplification module of the radio frequency power amplifier via asignal connection, wherein the control device comprises: an input signalprocessing module, configured to process an MRI radio frequency inputsignal into at least two signals, wherein a first signal of the at leasttwo signals is used for signal detection, and a second signal of the atleast two signals is used for signal amplification; a signal processingand control module, configured to receive the first signal and output acontrol signal, wherein the control signal controls a degree of theadjustment of the second signal; an adjustment module configured toadjust, based on the control signal, an amplitude and/or a phase of thesecond signal; and a delay module comprising a surface acoustic wavefilter, disposed between the input signal processing module and theadjustment module, configured to determine a delay of the second signal,wherein the signal processing and control module is further configuredto impose an adjustable delay on the control signal, so as to cooperatewith the delay module to ensure that the control signal and the secondsignal simultaneously reach the adjustment module; and the radiofrequency power amplification module configured to receive and amplifythe second signal to generate an output signal.